Horn or amplifier



Patented July 21,1925.

UNITED STATES PATENT OFFICE.

GEORGE W. BULLEY, OF AKRON, OHIO, ASSIGNOR TO THE MILLER RUBBER COMPANY,

OF AKRON, OHIO, A CORPORATION OF OHIO.

HORN OR AMPLIFIER.

Application filed April 11, 1924. Serial No. 705,891.

T 0 all whom it may concern:

Be it known that I, Gnonon IV. BULLEY, a citizen of the United'States, and resident of Akron, in the county of Summit and State of Ohio, have invented certain new and useful Improvements in Horns or Amplifiers, of which the following is a specification.

My present invention relates to resonating bodies and particularly to sound amplifying apparatus. M invention is particularly adapted to t e manufacture of resonating horns such as are used in the construction of. loud speakers and phonographs.

Very little is known about the scientific design of such apparatus either as to the effects of shape, finish or materials, as evidenced by the variety of designs exhibited in such articles now on the market. The general opinion of the public and of manufacturers is that metallic horns, especially when made of thin metals, and some of other hard and sonorant materials tend to vibrate, themselves, in addition to their function of surrounding a vibrating air column and thereby add certain foreign sounds, or impart a tinny quality to the speech or music. The objection to such horns is so universal that many efforts have been made to produce horns of non-metallic nature and the majority of suchdevices now on the market are made of cellular hard rubber, wood, fiber, or glue and plaster compositions. Of these materials, wood can be produced in complicated shapes only at great expense, fiber is difficult to form in the required shapes, so that the article must be made in pieces, the glue and plaster is too breakable and heavy, and cellular hard rubber has surpassed -all of these in'ease of production, uniformity and tonal quality. Cellular hard rubber horns are molded of one piece con-. struction, and where a complicated shape is required, it is often difficult and sometimes impossible to produce such design in this material. Such a shape is illustrated in the accompanying drawings.

I have found that the flaring or bell portion of a horn is more liable to produce distort-ion of the sounds than the parts of the horn nearer the diaphragm, and that while cellular hard rubber is an ideal material for that portion of the horn where the ratio of horn thickness to diameter is relatively small, its advantage over other materials is not so apparent in other parts of the horn. I have found for instance, that the small part of the horn near the diaphragm may be made of aluminum or other metal which may be cast in complicated shapes quite impossible to produce in cellular hard rubber and the remainder of the horn may be made of cellular hard rubber. Such a horn I also find to be better balanced in weight in some shapes of horns.

In order to insure absolute continuity of the sound passage free from air leaks which would prevent certain sounds from bein reproduced and in order to prevent any vi ration due to jointed contacts, I mold the rubher and metal portions in interlocking relation. This is done by first casting the metal part having openings therethrough and placing this in a mold for producing the rubber portion. In the molding operatlon the rubber flows through the openings and interlocks with the metal. N o cement, glue, rivets or screws are necessary and an air tight joint is obtained. The metal part may be machined at the small end to accurately fit the sound box.

In order that my invention ma be more readily understood, I have appen ed hereto 3. drawing illustrating the same, in whichgigure l is a perspective View of a horn, an

Fig. 2 is a fragmentary sectional view on a larger scale.

Referring by reference characters to this drawing, the numeral 1 designates the metal portion of the horn, and 2 the cellular portion of cellular hard rubber. The metal portion is provided with a plurality of annularly arranged holes 2 into which the rubber flows in the moldin operation, and thus forms a firm interloc ing connection. Preferably, the perforated portion is of reduced thickness, formed by rebating the inside of the mouth of the metal portion, so that the inner surface of the rubber portion is flush with the inner surface of the metal portion, and the metal portion may be provided with an external flange 1' against which the rubber abuts.

It will be understood that the material used in the small part of the horn near the neck, does not have as much effect on the quality of the sound as the material used in the bell, and while I prefer to use cast metal for the neck of the horn, I do not wish to be limited to metal castings, as the neck might be formed of sheet metal, or other solid material.

Having thus described my invention, what I claimis 1. An amplifying horn comprising a metallic neck portion and a hard rubber sound amplifylng or hell Dart. having its inner reduced end molded around the end of the metallic neck, and with its inner surface flush with the inner surface of the metal neck, means being rovided on the neck end around said end, and with its inner surface 20 flush with the inner surface of said metal part, means being provided on said metal end for interlocking with the rubber part.

In testimony whereof, I aflix my signature.

GEORGE W. BULLEY. 

